Python如何检查迭代器工具链中是否已到达最后一个元素？

Question

for elt in itertools.chain.from_iterable(node):

if elt is the last element:
  do statement

我如何实现这一目标

Answer 1

您可以通过使用 iter.next() 在 while 循环中手动推进迭代器，然后捕获 StopIteration 异常:

>>> from itertools import chain
>>> it = chain([1,2,3],[4,5,6],[7,8,9])
>>> while True:
...     try:
...         elem = it.next()
...     except StopIteration:
...         print "Last element was:", elem, "... do something special now"
...         break
...     print "Got element:", elem
...     
... 
Got element: 1
Got element: 2
Got element: 3
Got element: 4
Got element: 5
Got element: 6
Got element: 7
Got element: 8
Got element: 9
Last element was: 9 ... do something special now
>>>